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APPENDIX II
BATTERY CALIBRATION
What is calibration?
Calibration is the process of updating the ‘100% capacity number’,
stored in the battery, to a new and more accurate value.
How is the battery calibrated?
The battery is calibrated by:
• Charging the battery to full capacity.
• Discharging the battery to a voltage level known to correspond to
zero stored energy (7.8VDC for the Intelligent Battery).
• Updating the ‘100% capacity number’ stored in the battery.
Why is calibration needed?
Calibration is needed to restore accuracy to the user information
displays appearing on the screen of the PowerBook and the LCD
displays of the PowerCenter. A second reason is to match the cali-
brated and actual capacity of the battery to allow it to supply power to
the proper discharge level when used in the PowerBook.
How do I know calibration is necessary?
Calibration may be necessary if you observe the PowerBook 'battery
charge' or 'time remaining' indicators to be inaccurate, or if a battery is
providing shorter than expected operating times. Jumps in the '%
Charge' display at full charge, or early cut off during discharge, also
indicate a need to calibrate the battery. These % changes are not
easily seen unless a digital "Gas Gauge" desk accessory or external
charger unit is used.
